Fans who’ve missed Johnny Carson since he signed off the air in 1992 may not realize it, but there’s still a late-night venue where they can catch his special brand of humor. That’s because the 79-year-old retired Tonight Show host has been moonlighting lately, sending jokes to his pal David Letterman that occasionally make it into the latter man’s CBS Late Show monologue. Carson has maintained a friendship with Letterman, even though his Tonight Show hosting gig went to Jay Leno.

While reading the newspaper every morning, Carson ”can think of five jokes off the bat that he wishes he has an outlet for,” explained former Tonight Show executive producer Peter Lassally, a Carson pal and current CBS senior vice president who was speaking to reporters at the Television Critics’ Association’s Winter Press Tour.

According to Lassally, Carson occasionally offers his ideas for punch lines to Letterman, who sometimes works them into the shtick that begins his nightly program. ”Johnny gets a big kick out of that,” said Lassally. ”I think the thing he misses the most is the monologue.” He said that Carson still watches late-night TV, usually in primetime using East Coast feeds, and is ”doing fine” despite a bout with emphysema.